Electrical switching device



Sept. 20, 1938. H. M. SALMOND ELECTRICAL SWITCHING DEVICE Filed July 2,1934 4 Sheets-Sheet l 48 JW 7421M /3 Qua;

Sept. 20, 1938. H. M. SALMOND ELECTRICAL SWITCHING DEVICE 4 Sheets-Sheet 2 Filed July 2, 1954 Fig.6a.

Sept 20, 1938. H. M. SALMOND ELECTRICAL SWITCHING DEVICE Filed July 2,1954 4 Sheets-Sheet 3 #04, Z Wz/M Sept. 20, 1938. H. M. SALMONDELECTRICAL SWITCHING DEVICE Filed July 2, 1934 4 Sheets-Sheet 4 0 3% W/3 B, B 2%, w; H fi w w a E UNA/MW M g "1 4 o o I T. .4 7 l L WAY w w Wm 1 71 W w 9 0 o E 0 M w JU i J 0 .1. N WW w a A? w j Z ,0 aura U n r mX 1 9 -l I |-I| 1-1 Aw n n MW a D.- o 7 ill? 5 Mi 0 m 9W M E 0 4 E 9 7 IT w F l\ m m m m air Be M ATTORNEY Patented Sept. 20, 1938 UNITED STATESPATENT OFFICE ELECTRICAL SWITCHING DEVICE Application July 2, 1934,Serial No. 733,520 In Great Britain July 28, 1933 17 Claims.

This invention relates to electrical switching devices of the kind inwhich a pendulum controls the operation of the switch contact elements.An object of the invention is to provide an electrical switching devicefor use upon vehicles and crafts in which the switch contact elementsare actuated by a comparatively powerful spring under control of apendulum subject only to small reaction.

Another object of the invention is to provide a switching device inwhich the switch contact elements are actuated by a spring operatedmember interconnected to a pendulum by a pivotally .mounted leverelement.

A still further object of the invention is to provide an automaticallyoperable switching device adapted to disconnect all electrical circuitsin a vehicle or craft in an accident.

With these and other objects in view, the invention will be betterunderstood from the following detailed description taken in connectionwith the accompanying drawings wherein:

Figure 1 shows an electrical switch controlled by a pendulum togetherwith a diagrammatic representation of a circuit controlled by theswitch.

Figure 2 shows a slightly difierent form of switch mechanism to thatshown in Figure 1.

Figure 3 shows a mechanism in which the pendulum is of a difierent formfrom that shown in Figures 1 and 2. i

Figures 4 and 4a show arrangements of mechanism employing a multiplecatch arrangement in side elevation and front view.

Figures 5 and 5a show a still further modification of a pendulum device.

Figures 6 and 6a show respectively side elevation and front view of amechanismland switch device arranged to be locked in operated andnon-operated positions.

Figures 7 and 7a show respectively side view and front elevation of aninstrument comprising a pendulum controlled switch device mounted in aprotecting case.

Fig. 8 is a vertical sectional view of my device taken on the lineIll-40 of Fig. 9, showing the switch mechanism in unset position, withignition circuit open.

Fig. 9 is a vertical sectional view taken on the line Il-Il of Fig. 8,showing the switch spring contact elements, and operating cams andlevers.

Fig. 10 is a vertical sectional view similar to Fig. 8, with the switchmechanism set and the ignition circuit closed.

Fig. 11 is a vertical section taken on the line iii-13 of Fig. 10. v

Fig. 12 is a horizontal sectional view taken on line H-ll of Fig. 10,showing details of the switch mechanism, and 1 Fig. 13 is a detail ofthe arcuate sector cam which engages the pendulum cam.

Referring to Figure 1 of the drawings, numeral 2 represents a pivotallymounted pendulum comprising a mass 3 and a mushroom shaped head 10 l,the pendulum being mounted by means of a ball 5 supported in a socketdevice 6 carried by bracket 1 itself secured to a mounting plate 8 ofthe device.

The switch mechanism comprises a rigid con- 15 tact element 9 providedwith a current conducting contact engaging a similar contact carried bythe leaf spring contact element I0. In addition a further rigid contactelement II is provided with a contact adapted to be engaged by a similarcontact carried by another leaf spring l2.

The switch is so arranged that it is adapted to be operated by a leafspring I3, sufllciently powerful to actuate springs l0 and II, butnormally engaged by the toe H of a lever device [5 carrying at its otherend a member l6 adapted to engage head 4. The lever 15 is pivotallymounted at I1 and is provided with a heel IS, the arrangement being suchthat spring I3 is normally retained in the position indicated in Figure1, but is released when the mass 3 of the pendulum is displaced, forexample, due to the tilting of the mechanism or as a result'oiexceedingly violent impact.

When spring I3 is released it opens the normally closed contact pointscarried by elements 9 and I0 and closes the contact carried by elementsII and I2 and the switch remains in this position until operating handleI9 is pressed downwardly to a sufllcient extent to force the end of 40spring I; into engagement with the heel ll of lever l5, whereby theelement [6 is'lifted clear of head 4 so that pendulum 2 can assume itsnormal position indicated in Figure 1.

Figure 1 shows how the switch controls the electrical supply resourceson a vehicle or craft which sources comprise battery 20 and generator2!. Normally one lead is taken from the battery output terminal to theelectrical system on a vehicle including the lamps and ignition coil as.well as various electrically operated devices. This lead is cut andconnected to a connector 22 itself connected by leads to normally closedcontacts 9 and III in such a manner that all currents supplied bybattery (it except to the selfstarter flow over the normally closedcontacts.

The generator 2| has its output terminal connected to one of elements itor 112, the other being connected to earth or to the other terminal ofthe generator, the arrangement being such that when spring l3 operatesspring contacts ill and N2, the generator is short circuited.

As will be noted the lever is provided with toe and heel parts l4 and itso arranged that the spring it engages the lever in a plane parallel andclosely adjacent to that through the center of the lever l5 so that,although the tension of spring it may be quite considerable, the forcesupplied by element 55 to the head 4 of the pendulum i is comparativelysmall.

Referring to Figure 2, the lever i5 controls a knife blade switchcomprising blade 23 and fixed contacts 24, a projecting catch 25 beingengaged by toe M of the lever l5, a helical spring 28 actuating theswitch and a projecting member 2i serving to reset the mechanism afteractuation as a result of an accident or the like.

Referring to Figure 3, this figure shows a slightly differently shapedlever l5 and an operating member 28 actuated by a helical spring adaptedto actuate a contact assembly substantially as indicated in Figure 1.The pendulum device shown in Figure 3 however, differs substantiallyfrom that described in Figures 1 and 2 and comprises a cam device 25carried by *arms 38 pivotally mounted at 86 upon a collar or the like32, itself mounted to pivot or rotate upon a pin or the like 38. Theelement l6 of lever l5 normally rests upon cam 29 and if the device isturned sideways the cam will move away from element it whereby the leverwill be released when the pendulum attains a predetermined angulardisplacement depending upon the length of cam 29.

In the case where the mechanism shown in Figure 3 may be subject toimpact in a forward direction the cam 29 will move forward in a forwarddirection causing release of the lever l5, with resultant operation ofthe switch.

The contactor 28 is mounted upon a spindle provided with hand operatedmeans so that upon rotation against the action of the operating helicalspring the catch 28 will engage heel ill of lever l5 and bring elementl6 into a position in which the pendulum and cam 29 assume the normalposition indicated in Figure 3.

In Figure 4, is shown a modification of the lever arrangement in whichtoe M of lever I5 does not engage the switch controlling elementdirectly but engages the long arm 35 of a lever 36 having a toe 31engaging the switch controlling element 38, a heel 39 being providedupon lever 36 for effecting restoration to normal of the mechanism. Theswitching device comprises a rotatably mounted drum 40 provided withconducting segments 4| and a contacting brush element 42. The switch maybe arranged to open or close the circuit as desired but the drum isactuated by a helical spring 43. The pendulum device takes the form of aflail 44 and lever I5 is provided with a cam 45 engaging a cam shapedportion 46 upon pendulum 44. The pendulum is pivotally mounted at 4'!upon a stud or the like 41 itself rotatably mounted in a supportingplate or the like 8. I

As will be observed, the point of engagement between lever l5 and thependulum of Figures 3 and 4 is vertically below the point of support ofthe pendulum. The shape of cams 29 and 45 is ensures such that thependulums when rotating angularly do not effect appreciable movement oflever l5, but the shape of cam and cam 45 is such that when thependulums move in a forward direction, a movement against the action ofthe switch actuating springs is effected and the angles of these camelements are so arranged that the pendulums do not release unless thedevice is subject to impact of considerable violence.

In Figures 5 and 5a is shown a modified form of the pendulum comprisinga mass 48 carried by arms e supported by a pivot support 55, the arms.orming a cam 5i adapted to engage the elemen it of lever l5, thearrangement being such that upon sldeway angular displacement of thependulum the element I6 is released from the cam 5i when the angle ofdisplacement attains 'a predetermined value and in the case of impact ina longitudinal direction the mass ill swings forward or backwardswhereby element i5 is again released from 'cam 5| thus enabling leveriii to release the switch controlling element.

In Figures 6 and 6a is shown a form of mechanism in which means areprovided for operating the contact assembly so as to disable theelectrical system upon a vehicle by means such as a key the device thusbeing capable of preventing unauthorized operation of a vehicle.

The pendulum and lever arrangement are practically identical to thosedescribed in connection with the previously described figures, and thecontact assembly is that shown in Figure 1 except that spring i3 ismounted adjacent the spring assembly and is adapted to eiTect actuationthereof by an extension i3 The means for actuating the switch assemblycomprises a rotatably mounted shaft 52 provided with a projecting arm 58adapted to operate springs l8 and it when the shaft is rotated in ananti-clockwise direction. A further arm 54 carried by the shaft servesto engage spring it to restore the same into set position in engagementwith the toe 3'! of lever 36.

In order to ensure correct positioning of the shaft 52, a cam 55 ismounted thereon and is adapted to be engaged by a spring 56 secured tothe mounting plate 8 of the instrument.

When the cam is shaped as shown the shaft has two normal positions of 90angular displacemerit, and inthe normally set position the arms 53 and54 are so disposed that they do not prevent operation of the device incase the lever l5 should be released by the pendulum.

The shaft 52 may be mounted by bracket elements fixed on the plate 8 andprovided with tubular extensions 51 housing split sockets 58 to whichthe shaft 52 is secured. In order to prevent unauthorized operation ofshaft 52 a spring 59 mounted upon tubular extensions 51 is adapted toengage the slot in sockets 58 from which it must be ejected by means ofa key 60 which may haveslots provided therein adapted to engage pinsdisposed in the slot in sockets 58 so as to prevent insertion ofkeysother than those intended to operate the mechanism. The tubularindent'in cam in which position the springs I0 and I2 open the batterycircuit of the car and short circuit the dynamo and disable the hightension system.

A spring 6| also mounted upon tubular extension 51 is adapted to engagethe slot in the socket 58 when this has been rotated 90, and uponwithdrawal of the key this spring locks the shaft 52 and the switchmechanism in the operated position.

Figures 7 and 70 show a practical embodiment of the invention in which aswitch mechanism comprising a contact assembly and automaticallyoperable release mechanism is mounted in a protective casing so as to becapable of being mounted .for example under the bonnet of a motor car.Electrical leads'are provided from the instrument to the battery anddynamo as well as to the high tension magneto if such is provided upon acar, and an additional earth connection is provided from the instrumentto effect the appropriate circuit changes.

Referring to Figure 7, numeral III indicates the bottom of a protectivecasing, ll being the top thereof capable of being secured to the bottomin any suitable manner. The mechanism of the instrument is mounted upona mounting plate 13 carried by a suitable number of posts 14 securedtothe casing bottom 18. The pendulum 15 is provided with a central camsurface 16 and is suspended from a support TI by means of extending lugswhich engage a pin 18 mounted in support I1 in such a manner thependulum is free to swing in planes at right angles to plate 13. Thesupport 11 is carried by a stud 19 fixed to plate 13 in such a mannerthat it is capable of rotation in a plane parallel to plate 13. The camI6 engages a triangular are shaped cam 88 carried by lever 8| pivotallymounted by pin and bracket means upon plate 13. Lever 8| is providedwith toe 82 and heel 83 which are engaged by the long arm of a leverdevice 84 pivotally mounted by pin and bracket means on plate 13.

The lever 84 is provided with toe 85 and heel '86 adapted to engage acam device 81 fixed upon a spindle 88 mounted by a pair of brackets uponplate I8 so as to be capable of rotation but fixed against endwaydisplacement, a resetting handle 89 being secured to an extension ofshaft 88 projecting through the protective casing. A helical spring 98is carried by shaft 88 and arranged to rotate the shaft in a clockwisedirection when cam 81 is released by lever 85. The contact assemblycomprises fixed contact elements 9| and 92 and spring contacts 98 and94. The cam 81 is provided with a projecting stud or pin 95 carrying aninsulating sleeve adapted to engage spring contacts 93 and 94, thearrangement being such that spring 98 is held in, a normally openposition as shown in Figure '7, but upon release of cam 81 by lever 84the stud 95 is rotated until it engages a stop 96 which is connected toa terminal which in its turn may be connected to the high tensionmagneto if such is employed upon a vehicle or craft whereby the same isswitched off when the instrument operates.

Stop 96 is insulatingly supported from mounting plate I3 and is providedwith binding post H3. The contact assembly is supported by a stud 4attached to mounting plate 13. The stud H4 is advantageously of metaland forms 'part of the switch circuit, and is electrically connected tomounting plate 13. Binding post I28 is attached to stud H4. Shaft 88 isjournalled in a pair of spaced supporting plates H8,

1, which are attached to mounting plate 18.

The insulating sleeve on stud 95 permits spring 98 to close its contactwith the contact upon element 9|v and subsequently the spring 94 isforced away from engagement with contact 92 whereby the circuit overthese contacts is opened.

When the instrument of the present invention is employed upon a vehicle,electrical leads are takenfrom the battery so that all the currentsupplied by the battery to the electrical system except the self-starteris normally flowing over contacts 92 and 94. Contact 9| is connected tothe dynamo output terminal and contact 93 is connected to the instrumentwhich is connected to earth. When the instrument operates it will beobserved that contacts 9! and 93 close before contacts 92 and 94 areopened, this has been found desirable in practice as the dynamo isdisabled before the battery circuit is open, whereas liability to damagethe electrical devices and lamps exists if the battery circuit is openedbefore the dynamo is put out of action.

When the instrument is employed upon a vehicle it is mounted so that thependulum hangs vertically downwards, centrally over cam 80, and when thevehicle is overturned or when it at tains an angle of approximately 45the cam 18 disengages cam 88, and, as a result of the action of spring90, lever 84 turns in an anticlockwise direction as shown in Figure 7due to the disengagement of toe 85 with cam 81, and lever 8| turns in aclockwise direction due to the disengagement of the long arm of lever 84with toe 82, and as soon as cam 18 releases cam 88 the lever 8| releaseslever 84 and this therefore releases cam 81 which is rotated so as toeffect closure of springs 9| and 93 and opening of contacts 92 and 94before coming into contact with the stop 96 whereby this element isconnected to earth. The radius of the cam 80 may be struck from thecenter of pin 19 so that no movement of lever 8i is produced when thependulum rotates in a plane parallel to plate 13. Alternatively, theradius may be struck from slightly above the center of pin 19 in whichcase a slight lift of the cam 88 and lever 8|, against the action ofspring 90, is produced when the pendulum is displaced from its normalcentral position and this arrangement tends to retain the pendulum in acentral position.

In the case where a vehicle is subject to impact,

the pendulum 15 moves forward owing to its inertia and cam 16 is causedto lift cam 80 and the long arm of lever 8| against the action of spring99 to a predetermined extent so as to prevent release in case of a minorimpact, for example, when the brakes of a vehicle are suddenly appliedor when a slight impact with another vehicle or an obstacle takes placewhich is not likely to cause serious injury to the driver or damage tothe vehicle. The inclination of the cam 18 is however, such that in thecase of a violent impact release of lever 8| takes place without fail.The inclination of carn-16 as indicated in Figure 7, is 45 and this hasbeen found to be suitable for practical purposes,

The casing comprising parts 18 and II is adapted to be mounted upona'vehicle, for example,

under the bonnet, and, to facilitate mounting,

a pair of lugs or the like I I8, I I9 are secured to the casing bottomwhereby the instrument may be secured in a horizontal position with thepart II of the'casing pointing in the direction of travel of thevehicle.

Electrical leads I00 soldered or sweated to tags 9.8 upon the contactassembly and secured by clamping devices 99 to the bottom of the casingare provided for connection to the electrical system upon a vehicle orcraft.

In the case of switch devices for use on aeroplanes it is desirable thatcams 45 and are shaped somewhat as indicated in dotted lines in Figure4a so as to tend to retain the pendulum in normal position although theinstrument is turned sideways or upside down. In order to enable themechanism to be reset, helical springs 840 and till may be provided uponthe pivot spindles of levers 34 and ill, Figure 7, tending to rotate thesame in a direction to effect disengagement, also a helical spring llllor the like may be attached to the pendulum l5 so as to tend to retainthe same in its normal position, the spring being capable of sufiicientextension to efiect release in case of impact. When a spring 7130 isattached to pendulum 715, the cam 30 may be shaped as shown in Figure 7aas the spring prevents disengagement between cams l6 and 80) except inthe case of violent impact. It is of course to be understood that thevarious parts of the device may be designed and constructed in variousother ways, and the various mechanisms arranged in other combinationsthan illustrated, and therefore I do not wish to be limited in anymanner except as set forth in the following claims.

Having thus fully described my invention, what I claim as new and desireto protect by Letters Patent is:

1. A switch for rendering inoperative the electrical circuits of avehicle upon a condition of collision or the like, comprising: aplurality of electrical contact elements, spring-biased means formaintaining said contact elements in contact under normal conditions,spring means effective to oppose and overcome said last-mentioned meansto open said contact elements, latch means for maintaining said lastspring means retracted andinoperative, pendulum means associated-withsaid latch means and eiiective to release the same upon the occurrenceof an abrupt acceleration or deceleration of the vehicle, said springmeans being provided with a manual positive control operable with asingle movement to reset said contact elements in closed position whensaid pendulum means has returned to normal position.

2. A switch for rendering inoperative the electrical circuits of avehicle upon a condition of collision or the like, comprising: aplurality of electrical contact elements, means for maintaining saidcontact elements in contact under normal conditions, means efiective toovercome said last mentioned means and open said contact elements, latchmeans for rendering said contact opening means inoperative, and pendulummeans having a cam element normally in positive locking abutment withsaid latch means but displaceable to release said latchmeans upon aswinging of the pendulum occasioned by an abrupt acceleration ordeceleration of the vehicle.

3. A switch for rendering inoperative the electrical circuits of avehicle upon a condition of collision or the like, comprising: aplurality of electrical contact elements, means for maintaining saidcontact elements in contact under normal conditions, means effective toovercome said last-mentioned means and open said contact elements, latcnmeans for rendering said contact opening means inoperative, pendulummeans associated with said latch means and efiective to completelyrelease the same upon the occurrence arsavoe of an abrupt accelerationor deceleration of the vehicle, and manually operable latch-resettingmeans for reclosing said electrical contact elements.

4. A switch for controlling the electrical circuits of a vehicle upon acondition of collision or the like, comprising: a plurality ofelectrical contact elements, means for normally maintaining at least onepair of said contact elements in closed-circuit relationship, means fornormally maintaining another pair of said contact elements inopen-circuit relationship, means effective to oppose and overcome eachof said two last-mentioned means and invert the normal contactpositions, latch means for rendering said contact-inverting meansineffective, and pendulum means associated with said latch means andeffective to release said latch means upon the occurrence of an abruptacceleration or deceleration of the vehicle.

5. An electrical switching device for rendering inoperative theelectrical circuit of a vehicle upon a condition of collision or thelike, comprising a plurality of electrical contact elements, a springactuated member electrically independent of said contact elements foractuating said contact elements, a lever, a pivotal support for saidlever, said pivotal support being attached to said lever at a pointalong the length thereof to divide said lever into two sections ofuneven length, means formed in the shorter of the two sections of saidlever for engaging said spring member and hold- .ing said member undertension, means engaging the free end of the other of said sections fortripping said lever and releasing said spring for actuat'ing saidcontact elements and pendulum means for controlling said last means.

6. An electrical switching device for rendering inoperative theelectrical circuit of a vehicle upon a condition of collision or thelike, comprising a plurality of electrical contact elements, a

spring member electrically independent of said contact elements foractuating said contact elements, a lever, a pivotal support for saidlever, means at one end of said lever for engaging and holding saidspring under tension, means engaging the other end of said lever fortripping said lever and releasing said spring for actuating said contactelements, pendulum means for controlling said last means and resettingmeans for resetting said lever after it is tripped.

7. An electrical switching device for rendering inoperative theelectrical circuits of a vehicle upon a condition of collision or thelike, comprising a plurality of electrical contact elements, a springmember electrically independent of said contact elements for actuatingsaid contact elements, a lever including catch means for holding saidspring member in a predetermined position, means associated with saidcontact elements for engaging said spring member when the latter isreleased by said catch means, pendulum means for engaging said lever torelease said catch means from said spring for actuating said con tactand resetting means for resetting said lever after it is released.

8. A switch for effecting changes of the electrical circuits uponvehicles and craft upon a condition of impact, comprising a vfreelysuspended pendulum, supporting means comprising a pair for maintainingsaid switch mechanism in actu-- spring action, a spring urged membernormally held in tensioned position by said pendulum and lever andadapted when released upon occurrence of impact to actuate said contactelements to eifect desired circuit changes and manually operableresetting means for resetting said lever after it is released.

9. An electrical switching device for rendering inoperative theelectrical circuits of a vehicle upon a condition of collision or thelike, comprising: a panel member, a pendulum' pivotally supported onsaid panel member, a first lever also pivotally supported on said panel,means attached to said first lever for slidably engaging said pendulum,said first lever having a first latch device, a second lever pivotedwith respect to said first lever and having an end engageable with saidfirst latch device of said first lever, a rotatable shaft, a springattached to said shaft, said second lever having a second latch device,means on said shaft for engaging said second latch device of said secondlever when said shaft is rotated against said spring, an electricalcontact device, and means for actuating said electrical contact devicewhen said shaft and said levers are released by movement of saidpendulum so that said shaft is rotated by the action of said spring.

0. An electrical switching device for rendering inoperative theelectrical circuits of a vehicle upon a condition of collision or thelike, comprising: a rotatable shaft, a spring attached to said shaft toprevent the rotation of said shaft except with or against the tension ofsaid spring, electrical contacts positioned to be actuated upon therotation of said shaft, a lever and latch device, means cooperating withsaid shaft for engaging said lever and latch device when said shaft isturned against thetension of said spring to hold said shaft in thistensioned position, a cam attached to said lever and latch device, and apendulum having means for engaging said cam to hold said shaft in saidtensioned position until a condition of collision or the like disengagessaid cam from said pendulum means.

11. An electrical switching device as set forth in claim 9 includingmanually operable means .for said shaft to reset the switching deviceafter in claim 10 including manually operable means attached to saidshaft to reset the switching device after the switching device has beenactuated.

13. In a crash actuatable safety switch, a switch mechanism, actuatingmeans for opening and closing said switch mechanism and comprising aspring normally maintaining said switch mechanism in a released positionand further comprising latch engaging means, a latch mechanismengageable with said latch engaging means for maintaining said switchmechanism in actuated position, a cam having cooperating meansengageable with said latch mechanism for locking the same, and apendulum having a cam surface engageable with said cam, whereby movementof predetermined amplitude of said pendulum beyond cam engaging positionunlocks said latch mechanism and releases said switch mechanism.

14. In a crash actuatable safety switch, a switch mechanism, actuatingmeans for opening and closing said switch mechanism and comprising aspring normally maintaining said switch mechanism in a released positionand further comprising latch engaging means, a latch mechanismengageable with said latch engaging means ated position, a cam havingcooperating means engageable with said latch mechanism for locking thesame, a pendulum having a cam surface engageable with said cam, andsupporting means comprising a pair of independent pivots for pivotallysupporting said pendulum with two degrees of rotative freedom, wherebymovement of predetermined amplitude of said pendulum beyond cam engagingposition unlocks said latch mechanismand releases said switch mechanism.

15. In a crash actuatable safety switch, a switch mechanism, actuatingmeans for opening and closing said switch mechanism and comprising aspring normally maintaining said switch mechanism in a released positionand further comprising latch engaging means, a latch mechanismengageable with said latch engaging means for maintaining said switchmechanism in actuated position, a cam having cooperating meansengageable with said latch mechanism for looking the same, a pendulumhaving a cam surface engageable with said cam, said cam having itsperiphery engageable with said pendulum cam surface substantially'in theform of a circular arc, and a pivot for supporting said pendulum formovement substantially parallel to the plane of said arc, said are beingsubstantially struck about said pivot as a center, whereby movement ofpredetermined amplitude of said pendulum beyond cam engaging positionunlockssaid latch mechanism and releases said switch mechanism.

16. In a crash actuatable safety switch, a switch mechanism, actuatingmeans for opening and closing said switch mechanism and comprising aspring normally maintaining said switch mechanism in 9. releasedposition and further comprising latch engaging means, a latch mechanismengageable with said latch engaging means for maintaining said switchmechanism in actuated position, a cam having cooperating meansengageable with said latch mechanism for locking the same, a pendulumhaving a cam surface engageable with said cam, said cam having itsperiphery engageable with said pendulum cam surface in the form of acircular arc, said pendulum cam surface being recessed in a directionsubstantially perpendicular to the plane of said arc, and a pair ofmutually perpendicular comechanism and releases said switch mechanism.

17. 'In a crash actuatable safety switch, a switch mechanism, actuatingmeans for opening and closing said switch mechanism and comprising aspring normally maintaining said switch mechanism in a released positionand further comprising latch engaging means, a latch mechanismengageable with said latch engaging means for maintaining said switchmechanism in actuated position, a cam having cooperating meansengageable with said latch mechanism for locking the same, a pendulumhaving a cam surface engageable with said cam, said cam havingv itsperiphery engageable with said pendulum cam surface in the form of acircular arc,'said pendu lum cam surface .being recessed in a directionsubstantially perpendicular to the plane of said arc, and a pair ofmutually perpendicular coopersaid pendulum moves perpendicular to theplates of said. are being positioned substantially above the point wheresaid cam arc meets said cam surface when said pendulum is in normalposition, whereby movement of predetermined amplltude of said pendulumbeyond cam engaging positlon unlocks said latch mechanism and re leasessaid switch mechanism.

HUBERT MACKENZIE SALMOND.

